3. TECHNICAL BRIEF
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3.8.5 Peripheral
The peripheral subsystem contains the peripherals shared by the modem ARM processor (ARM11 data access
only), the application processor (Scorpion), the mobile display processor (MDP4), the application data mover
(ADM), and aDSP audio (ADSP_A). The peripheral bus has three bus partitions (FPB1, FPB2, and FPB3 [SPB]) that
allow concurrent access by different masters.
Partitioning was done in a way to help BW capacity on the system. The application data mover is used to move
data to/from the high-bandwidth peripherals. Low bandwidth peripherals (such as the UART, I2C, and GPIO) and
some chip configurations (certain block control registers) reside on the slow peripheral bus, sourced by a bridge
tied to the fast peripheral bus.
3.8.6 WCDMA Subsystem
The MSM8255 WCDMA subsystem performs the data conversions and signal processing necessary to maintain
the WCDMA air interface between the handset and the base station (and also the WCDMA network). The
subsystem components include:
-Searcher engine
-Demodulating fingers
-Combining block
-Frame deinterleaver
-Viterbi decoder
-Reverse link subsystem
-Turbo decoder
On the forward link traffic channel, the WCDMA subsystem searches, demodulates, and decodes incoming pilot,
sync, paging, and traffic channel information. It extracts low bit-rate packet data from the forward link traffic
channel and sends the packet data to the vocoder for processing. On the reverse link, the WCDMA subsystem
processes the packet data from the vocoder and modulates the reverse traffic channel.